The present invention relates to a conversion dilator for use with dilatation catheters. More particularly, the present invention relates to an adapter for converting a dilatation catheter for use with a smaller size guidewire.
Catheters are well known for use with the human body as part of diagnostic or treatment procedures. Such devices are typically introduced through body lumens such as blood vessels and are advanced to the sight designated for diagnosis or treatment, which sight may be a particular vessel or organ. For example, it is well known in percutaneous transluminal coronary angioplasty (PTCA) procedures to introduce a small diameter catheter into a stenosis portion of a blood vessel caused by arteriosclerosis or the like. The PTCA procedure typically includes inserting such a catheter equipped with a dilator such as a balloon at its tip into the stenosis portion of the blood vessel and inflating the dilator so as to dilate the stenosis portion of the blood vessel, thereby improving blood flow at the distal side thereof.
During such PTCA procedures, a guidewire is typically first introduced into the blood vessel and positioned within the blood vessel at the area of the stenosis portion. The catheter equipped with the dilator is then inserted over the guidewire and advanced through the blood vessel to the area of treatment, for carrying out the necessary procedure. After dilation of the stenosis portion of the blood vessel, often times a vascular stent is implanted into the blood vessel in order to maintain the blood vessel in an open position.
Catheters and guidewires are supplied in a variety of sizes and diameters. Specific applications and procedures typically involve use of specific size catheters and guidewires. For example, due to the tortuous path of blood vessels in cardiology procedures, cardiologists typically prefer smaller diameter guidewires such as a 0.018 inch diameter catheter, since they include features which are amenable to such uses, including flexibility. On the other hand, radiologists may prefer to use a larger diameter catheter, such as a 0.035 inch catheter, for cost and ease of use for a particular application.
It is common place for end users such as physicians carrying out catheterization procedures to become accustomed to using one particular size guidewire in such procedures. Such a physician would therefore be reluctant to incorporate catheter systems which require use of a different size guidewire. For example, while a physician typically may prefer to use a 0.018 inch guidewire due to specific characteristics including tip transition, column strength, pushability, trackability and tensile strength, catheters systems which are designed for use with a different size guidewire, such as a 0.035 inch guidewire, are becoming more common place, for example, in percutaneous catheterization procedures, and specifically for those procedures involving delivery and employment of peripheral stents.
Accordingly, it is desirable to provide for the use of a smaller diameter guidewire with a larger diameter dilatation catheter.
The present invention is directed to a device in the form of a conversion adapter for reducing an internal lumen of a catheter so as to accommodate a guidewire having a diameter substantially smaller than the internal lumen of the catheter. As indicated, oftentimes a specific catheter, such as a balloon catheter, includes a lumen of a specific size inner diameter, such as 0.035 inches. The guidewire initially introduced into the vessel, however, may be of a much smaller size diameter, such as a 0.018 inch guidewire. While it may be possible to advance the catheter over the smaller diameter guidewire, doing so can result in a variety of problems, such as a drastic transition between the catheter tip and the guidewire created due to the drastic change in diameter between the two. Additionally, strength of the delivery system may be compromised due to the difference in size between the guidewire and catheter, creating a channel for the guidewire to twist or bunch up.
Accordingly, the present invention provides a catheter system including a conversion adapter for converting the inner lumen of a catheter to accommodate a guidewire having a diameter which is substantially smaller than the internal lumen of the catheter. The adapter is positionable within the internal lumen of the catheter. The adapter has an external diameter which is substantially equal to the internal lumen of the catheter and further includes a smaller internal lumen which is substantially equal in diameter to the guidewire and is therefore capable of accommodating the smaller diameter guidewire therethrough. Preferably, the adapter extends within the internal lumen of the catheter along the entire length thereof, and preferably extends beyond the length of the catheter, including a flexible tapered tip at the end portion. In particularly preferred embodiments, the external diameter of the adapter is about 0.035 inches, and the internal lumen of the adapter includes an internal diameter of about 0.018 inches for accommodating a guidewire of about the same diameter.
The present invention further provides a catheter system for use with a first guidewire having an external diameter and a second guidewire having an external diameter smaller than the first guidewire. The catheter system includes a catheter having a lumen defining an internal diameter capable of accommodating the first guidewire. The system further includes an adapter selectively positionable within the lumen of the catheter, with the adapter having an external diameter substantially equal to the internal diameter of the lumen of the catheter and further including a lumen having an internal diameter capable of accommodating a second guidewire of a smaller diameter than the first guidewire.
The adapter is preferably removably slidable within the lumen of the catheter. As such, the adapter can be adjusted so as to extend beyond the length of the catheter, and can be selectively removed from the lumen of the catheter such that the catheter can then accommodate the first guidewire of a larger diameter.
In particularly preferred embodiments, the catheter includes an expandable balloon portion, which may be used in conjunction with a radially expandable stent positioned thereabout for transluminal implantation. Furthermore, a sheath may extend about the entire catheter assembly for covering the catheter system including the stent during delivery to an area of implantation within a vessel.
Further, the present invention provides a catheter system for reducing the internal diameter of a lumen of a catheter. The catheter system includes a catheter having a lumen, and an adapter slidably positioned within the lumen of the catheter. The adapter extends beyond the length of the catheter and includes an outer diameter substantially equal to the lumen of the catheter and an inner diameter defining a lumen which is smaller than the lumen of the catheter.
Still further, the present invention provides a catheter system including a kit of parts for use with a plurality of guidewires having different diameters. Such catheter system includes a catheter including a lumen defining an internal diameter, and a plurality of adapters selectively positionable within the lumen of the catheter. Each of the plurality of adapters includes an external diameter which is substantially equal to the internal diameter of the lumen of the catheter. Moreover, each of the plurality of adapters further includes a lumen defining mutually distinct internal diameters capable of uniquely accommodating one of the plurality of guidewires therethrough. As such, a catheter system capable of mutually exclusive use with a plurality of different diameter guidewires is provided.